1. Field of the Invention
The present invention relates to splash-type lubrication systems for change-gear transmissions and, in particular, to an improved shroud structure for such transmissions which will reduce churning losses and assure proper lubrication of bearings on the main shaft.
2. Description of the Prior Art
Splash-type lubrication systems for vehicular change-gear transmissions are well known in the prior art. Briefly, a lubricant sump in the lower portion of the transmission housing is filled with lubricant, and the action of the transmission gears rotating through the sump will sling, splash, drip and/or otherwise direct lubricant to gear meshes and/or bearings. So-called splash-type lubrication systems, while providing somewhat inelegant but effective lubrication, are not totally satisfactory, as a relatively deep sump is required to assure that each gear will rotate therein, resulting in relatively high churning losses and heat generation.
Prior art attempts to minimize churning losses and heat generation have included pressurized systems with a xe2x80x9cdry sumpxe2x80x9d and relatively shallow troughs used to minimize the level of lubricant in which each gear layer will rotate. Examples of such prior art solutions may be seen by reference to U.S. Pats. No. 5,505,112; 5,050,451; 5,279,391 and 4,356,889, the disclosures of which are incorporated herein by reference. These solutions were not totally satisfactory for certain applications, as they tended to be somewhat complicated, expensive and/or did not assure that a significant amount of lubricant would be directed to bearings on the main shaft.
In accordance with the present invention, the drawbacks of the prior art are minimized or overcome by the provision of a relatively simple and inexpensive splash-type lubrication system for transmissions which will assure an adequate supply of lubricant to the drive gears and the bearings supporting drive gears on the transmission main shaft/output shaft. The above is accomplished by providing a relatively close-fitting gear isolation shroud around almost the entirety of the forwardmost countershaft gears, the upper opening of the shrouds allowing the countershaft gears to mesh with input and/or main shaft gears and acting as a director to direct splashed and flung lubricant toward the drive gears and the bearings supporting gears on the main shaft. The shroud will define troughs through which the countershaft gears rotate and in which only a reduced level of lubricant is maintained to reduce churning losses.
Accordingly, it is an object of the present invention to provide a relatively simple and inexpensive splash lubrication system that will assure an adequate supply of lubricant to the bearings and gears carried by the main shaft and will reduce churning losses of the transmission.
This and other objects and advantages of the present invention will become apparent from a reading of the following description of the preferred embodiment taken in connection with the attached drawings.